(19)
(11) EP 0 409 663 A3

(12) EUROPEAN PATENT APPLICATION

(88) Date of publication A3:
05.08.1992 Bulletin 1992/32

(43) Date of publication A2:
23.01.1991 Bulletin 1991/04

(21) Application number: 90308016.6

(22) Date of filing: 20.07.1990
(51) International Patent Classification (IPC)5: G11B 7/24, G11B 7/26, G11B 7/00, B29D 17/00
(84) Designated Contracting States:
DE FR GB

(30) Priority: 21.07.1989 JP 190396/89

(71) Applicant: JAPAN SYNTHETIC RUBBER CO., LTD.
Tokyo 104 (JP)

(72) Inventor:
  • Sakai, Naomi
    Ciba-shi, Chiba-ken (JP)

(74) Representative: Lamb, John Baxter et al
MARKS & CLERK, 57-60 Lincoln's Inn Fields
London WC2A 3LS
London WC2A 3LS (GB)


(56) References cited: : 
   
       


    (54) Optical disc, preparation thereof and reading method


    (57) The optical disc of the present invention has a transparent substrate provided on the surface opposite to the surface of a metallic reflective film in contact with a recording layer, and reading of a predetermined informa­tion is performed by permitting a laser beam to be inci­dent from the transparent substrate side. That is, light is reflected on the surface on the opposite side to the surface of the metallic reflective film in contact with the recording layer, and by employment of such a means, it becomes possible to enhance the reflectance in the metal­lic reflective film, and also the difference in surface reflectance between the concavity and the convexity is ef­fectively corrected a the uneven pit portion with a memorized information.





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